Process for forming an insulated container



1964 E. L. KENNEDY ETAL 3,120,570

PROCESS FOR FORMING AN INSULATED CONTAINER Filed April 20, 1961INVENTORS. EDWARD L. KENNEDY G, RIACH GLEN ATTORNEYS United StatesPatent Ofifice 3,120,570 Patented F eb. 4, 1964 3,120,570 PRGCESS FQRFGRNQNG AN INULATED CONTAINER Edward L. Kennedy, North Hollywood, andGlen G. Riach, Los Angeles, Calif, assignors to Southern CaliforniaPlastic Company, Glendale, Calif, a corporation of California Filed Apr.20, 1961, Ser. No. 104,293 Claims. (Cl. 264-45) This invention relatesto a process of forming an insulated container and particularly to sucha process and article wherein a pair of telescoping elements formed of athermoplastic material are spin-welded together to form a unitarystructure, said structure having foamed plastic insulating materialsubstantially filling the cavity formed by the telescoping elements.

It is an object of the present invention to provide a process forforming an insulated container wherein a liner is telescopicallyreceived in a shell to form an insulating space therebetween and sealedthereto by spinwelding to prevent subsequent leakage or breakage at theseal.

It is a further object of the present invention to provide such aprocess wherein the space between the liner and shell is substantiallyfully filled with a foamed plastic insulating material.

It is another object of the present invention to provide such a processwhereby an insulated container may be readily and economicallymanufactured.

Yet another object of the present invention is to pro vide a processwhereby an insulated container formed of thermoplastic material whichmay be subjected to considerable abuse and excessive temperatureswithout breaking is manufactured.

These and other objects and advantages of the present invention will bereadily apparent, it is believed, from the following detaileddescription of preferred embodiments thereof when taken in connectionwith the accompanying drawings in which FIG. 1 is a vertical explodedsectional view of the telescoping elements prior to assembly;

FIG. 2 is a vertical sectional view, partially in section, of one formof the completed insulated container;

FIG. 3 is an enlarged partial sectional view of the juncture of theelements prior to spin-welding;

FIG. 4 is an enlarged partial sectional view, similar to FIG. 3, afterspin-welding;

FIG. 5 is an enlarged partial sectional view of the juncture of theliner and shell.

In general, the process of the present invention includes the forming ofa liner adapted to be telescopically received within a shell, said linerand shell being formed of a thermoplastic material, placing a selectedfoamable plastic material into the cavity of the shell and spin weldingthe shell to the telescopically received liner while simultaneouslyallowing the foamable material to fill the space between the liner andshell to complete the insulated container.

Referring now to the drawings, the insulated container includes a liner10, telescopically received within a shell 12. The liner and shell maybe generally cylindrical in form, each having a common longitudinalaxis. The shell 12 includes 'a generally cylindrical wall 14 and a base16. The top portion 18 of the wall 14 is provided with a generallyV-shaped rim 20.

The liner 19 includes a liner wall 22, a liner base 24 and a bonnet 26.The liner wall 22 may be generally cylindrical in form, and may betapered, having a progressively decreasing cross sectional area from thetop 28 to the liner base 24. The bonnet 26 is formed integrally with thetop 28 and projects downwardly to form a space 4 9 between the wall 22and the inner periphcry 42 of the bonnet 26. The lower extremity 44 ofthe bonnet 26 includes a flange 46, a skirt 4-8 and a support ring 49.The skirt 43 and support ring 4? define a generally V-shaped annulargroove 50 adapted to receive the rim 20. The rim 2% when inserted intothe groove Si), may make frictional contact with the skirt 48, an innersupport ring 4-9 or the flange 46. Preferably, the frictional contactbetween the rim 20 and the bonnet 26 is against either the support ring49 or the skirt 48.

When the liner It) is telescopically received within the shell 12 andthe rim Zil is frictionally seated within the annular groove 59, theliner and shell define a substantially uniform space 54 therebetween.This space 54 and the space 4% may be filled with any insulatingmaterial having a low heat transfer coefficient. For example, foamedplastics, such as polystyrene and the like may be preformed and insertedinto the shell and the liner thereafter positioned. As thus assembled, acomplete insulated container is formed.

As a part of the present invention it has been determined that the linerand shell may be sealed together without the use of adhesives or thelike by forming both the shell and liner from the same thermoplasticmaterial and spin-welding the elements together. Any thermoplastic wellknown in the art may be used. Examples of such materials arepolyethylene, polyvinylchloride, polyvinylacetate, polystyrene,polytetrafiuoroethylene, polytrifiuorochloroethylene,polymethylmethacrylate, polypropylene, the acrylics, nylons and othersimilar addition and condensation polymers of the thermoplastic group.While any thermoplastic may be used, the preferred material should beselected from those having good heat resistance, low thermal transfercoeificient and high impact strength. Linear polyethylene andpolypropylene are quite satisfactory materials from which to form theliner and shell.

In order to achieve a uniform seal between the liner 1i and the shell 12it is necessary that the rim 20 and groove 50 be so formed as to permitthe rapid rotation of the shell with respect to the liner when the rim20 frictionally engages one of the surfaces defining the groove 5%. Therapid spinning while a surface of the shell frictionally engages asurface of the liner generates suflicient heat to melt the thermoplasticat the frictional interface. Thus, as seen in FIG. 4, the rim 20 becomesin effect a physical part of the bonnet 26, there being substantially novisible separation between the engaging friction surface of the rim 2%and the engaged friction surface of the bonnet 26.

While it is possible to preform an insulating material, insert the sameinto the shell 12 and assemble the shell and liner in, as a further partof the present invention it has been determined that the spaces 54 and44 may be readily and conveniently filled by utilizing a foamableplastic material such as, for example, polyurethane which is foamed insitu during the spin-welding operation. Thus, prior to inserting theliner it) into the shell 12, a predetermined amount of unreacted plasticwith a suitable catalyst and foaming agent is placed in the bottom ofthe shell 12. Prior to the foaming reaction taking place the shell andliner are assembled, the frictional surfaces of the rim 2t) and elementsdefining the groove 50 engaged, and then, during the course of thefoaming reaction the shell is spun with respect to the liner. Thespinning accomplishes two purposes. As above described, it causes theshell to be welded to the liner. in addition, the forces caused by therotation of one element with respect to the other causes the foamingmaterial to be thoroughly mixed prior to expansion through the spaces4-0 and 54.

Since, in many cases, welding is accomplished prior to the completion ofthe foaming reaction, bonnet 26 is provided with a small hole 60 toallow air entrapped in the space 40 to escape during the foamingreaction.

The quantity of foarnable plastic to be used will be determined by thevolume of the spaces 54 and 4!) defined by the joined shell and liner.While the resulting volume of foamed material can be controlled quiteaccurately, in order to provide reasonable manufacturing tolerances thebase 16 is preferably concave, while the base 24 is preferably convex.By so forming the respective bases :1 reasonable variation in quantityof foamable plastic may be accommodated since the bases 16 and 24 maynow be forced outwardly and inwardly respectively to allow for slightexcesses of the foamed material.

The minimum lateral distance between the outer surface of the wall 22and the inner surface of the wall 14 should be on the order of at least4; inch in order to permit ready flow of the foaming plastic throughoutthe spaces 40 and 54. If this distance is substantially less thanapproximately 4; inch, friction between the foaming plastic and thewalls 20 and 22 may prevent the foaming material from completely fillingthe spaces 40 and 54.

Any plastic material capable of being controllably foamed may be used asthe insulating material. Thus, the polystyrenes and polyurethanes andthe like readily adapt themselves for use in this process. The resultingunicellular material elfectively thermally insulates the wall 22 of theliner from the surrounding environment.

The following specific example is illustrative of the process of formingthe insulated container:

A liner and shell as above described and as illustrated in FIG. 1 wasformed of linear polyethylene. Approximately 10 grams of a Voracel Aformulation 2 foamable polyurethane was placed inside the shell 12. Thismaterial is described in the Dow Chemical Company Bulletin VR-l entitledPolyethers in Rigid Urethane Foams and includes a mixture of toluenediisocyanate, a polyether, monofluorotrichloromethane, triethylenediamine and a silicone compound. The ratios of these materials wereapproximately 49.0 parts by weight toluene diisocyanate, 0.25 part byweight silicone compound, 37.5 parts by weight of a polyether, 13.0parts by weight monofluorotrichloromethane, 0.25 part by weighttriethylene diamine.

The shell 12 was held in a chuck, illustrated in phantom at 62 in FIG.2. The liner 10 was placed in a chuck, illustrated in phantom at 64, andthe shell and liner joined by frictionally engaging the rim in thegroove 50. The chuck 62 was rotated by suitable means (not shown),having a slip clutch thereon. As the foam reaction commenced, the shellwas spun with respect to the liner at a speed of approximately 3000 rpm.After several seconds the shell was welded to the liner, rotation ceasedand rotation taken up by the slip clutch (not shown). The completedcontainer was removed and carefully cut in half along its vertical axis.An examination of the device showed that the seal between the rim 20 andthe elements defining the groove 50 was substantially uniform across theinterface and that the polyurethane foam completely filled the spaces 40and 54.

A second container was foamed by the above process, removed from thechucks and allowed to cool. The container was then filled with ice water(32 F.), covered with a plastic cap (not shown) and set aside for onehour. The temperature of the water in the container was then taken andshown to be approximately 39 F. The container was then emptied andsubjected to a temperature of 180 F. for twenty minutes, then tumbledand otherwise subjected to abuse and the weld examined. The weld wasuniform throughout the friction surface between the rim and the elementsdefining the groove.

It will be apparent that any other thermoplastic material may besubstituted for the linear polyethylene illustrated 4 in the aboveexample. It will be further apparent that other polyurethane foams,either rigid, semirigid or flexible, varying in density approximatelyfrom 1 pound to 40 pounds per cubic foot or any other foaming plasticmaterial may be substituted for the polyurethane foam set forth in theabove example.

The quantity of foaming material to be used will of course be determinedby the volume of space to be filled which in turn will be determined bythe relative sizes and form of the shell and liner. For example, thecontainer illustrated in FIG. 1 is in the form of an insulated bottle orjug. A modified form of the insulated container is illustrated insection in FIG. 5.

This container may be in the form of a tumbler wherein the upper lip26:: of the liner 10a is relatively thicker than the lower portion ofthe liner 10a. The skirt 48a and support ring 490 define an annulargroove 50a adapted to receive the rim 20a of the shell 12a. The wall 22aof the liner 10a tapers inwardly from the upper lip 26a so as to definea space 54a between the liner 10a and the shell 12a. The wall 14a of theliner 12a is provided with a hole 60a below the rim 20a and adjacent theupper lip 26a. By this construction an insulated tumbler may be formedin the manner above described. Such a tumbler was manufactured by theabove described process using polypropylene to form the liner and shelland the above described polyurethane as insulating material. Theinsulated tumbler was satisfactory in all respects.

Having fully described our invention, it is to be understood that we donot wish to be limited to the details set forth, but our invention is ofthe full scope of the appended claims.

We claim:

1. A process for forming an insulated container comprising the steps of:forming a shell and a liner from a selected thermoplastic, said linerbeing adapted to be telescopically received in said shell to define aspace therebctween, said shell and said liner each having an annularsurface adapted to be frictionally engaged one with the other upon axialtelescoping movement of the liner with respect to the shell; placing afoamable plastic into said shell, inserting said liner into said shellto engage said surfaces; and spinning said shell with respect to saidliner while maintaining said surfaces in frictional contact andsimultaneously permitting said plastic to foam and fill said spacewhereby said liner is welded to said shell and the insulated containeris formed.

2. A process for forming an insulated container comprising the steps of:forming a shell and a liner from a selected thermoplastic, said linerhaving a lower and an upper portion, said lower portion being adapted tobe telescopically received in said shell to define a space therebetween,said upper portion having means defining an annular groove, said shellhaving an upper annular rim adapted to be received in said annulargroove upon axial telescoping movement of the liner with respect to theshell, placing a foamable plastic into said shell; inserting said linerinto said shell to frictionally engage said rim with said means definingsaid annular groove; and spinning said shell with respect to said linerand simultaneously permitting said plastic to foam and fill said spacewhereby said insulated container is formed.

3. A process as claimed in claim 2 wherein said thermoplastic is linearpolyethylene and said foamable plastic is polyurethane.

4. A process for forming an insulated container from a linertelescopically received within a shell to define a space therebetween,the shell and liner being formed from a selected thermoplastic and eachhaving a surface adapted to be frictionally engaged, one with the other,upon axial telescoping movement of the liner with respect to the shell,comprising the steps of: placing a foamable plastic into said shell,inserting said liner into said shell to engage said surfaces andspinning said shell with respect to said liner and simultaneouslypermitting said plastic to foam and fill said space whereby saidinsulated container is formed.

5. A process for forming an insulated container comprising the steps of:forming a shell and a liner from a selected thermoplastic, said linerhaving a lower and an upper portion, said lower portion being adapted tobe telescopically received in said shell to define an annular spacetherebetween, the lateral distance between the outer surface of saidlower portion and the inner surface of said shell being on the order ofat least one-eighth inch, said upper portion being provided with abonnet and means defining an annular groove carried by said bonnet, saidshell having an upper annular rim adapted to be received in said annulargroove upon axial telescoping movement of the liner with respect to theshell; placing a predetermined amount of a foamable plastic into saidshell, inserting said liner into said shell to frictionally engage saidrim with said means defining said annul-ar groove; and spinning saidshell with respect to said liner and simultaneously permitting saidplastic to foam and fill said space whereby said insulated container isformed.

6. A process as claimed in claim 5 wherein said thermoplastic ispolyethylene and said foamable plastic is polyurethane.

7. A process as claimed in claim 5 wherein said thermoplastic ispolypropylene and said foamable plastic is polyurethane.

8. A process for forming an insulated container comprising the steps of:forming a shell and a liner from a selected thermoplastic, said linerhaving a lower and an upper portion, said lower portion being adapted tobe telescopically received in said shell to define an an nular spacetherebetween, said upper portion being provided with a skirt and asupport ring which define an annular groove, said shell having an upperannular rim adapted to be received in said annular groove upon axialtelescoping movement of the liner With respect to the shell; placing apredetermined amount of a foamable plastic into said shell, insertingsaid liner into said shell to frictionally engage said rim with saidannular groove; and spinning said shell with respect to said liner toform a uniform continuous seal between said shell and said liner andsimultaneously permitting said plastic to foam and fill said spacewhereby said insulated container is formed.

9. A process as claimed in claim 8 wherein said thermoplastic ispolyethylene and said foamable plastic is polyurethane.

10. A process as claimed in claim 8 wherein said thermoplastic ispolypropylene and said foamable plastic is polyurethane.

References Cited in the file of this patent UNITED STATES PATENTS1,309,757 Kempton July 15, 1919 2,393,883 Broderson Jan. 29, 19462,439,716 Canfield et a1 Apr. 13, 1948 2,539,524 Joseph Jan. 16, 19512,753,642 Sullivan July 10, 1956 2,898,634 Alderfer Aug. 11, 19592,933,428 Mueller Apr. 19, 1960 2,948,430 Teague et a1 Aug. 9, 19602,976,577 Gould Mar. 28, 1961 2,977,639 Barkhulf et al. Apr. 4, 19613,002,870 Belgrade et al. Oct. 3, 1961

1. A PROCESS FOR FORMING AN INSULATED CONTAINER COMPRISING THE STEPS OF:FORMING A SHELL AND A LINER FROM A SELECTED THERMOPLASTIC, SAID LINERBEING ADAPTED TO BE TELESCOPICALLY RECEIVED IN SAID SHELL TO DEFINE ASPACE THEREBETWEEN, SAID SHELL AND SAID LINER EACH HAVING AN ANNULARSURFACE ADAPTED TO BE FRICTIONALLY ENGAGED ONE WITH THE OTHER UPON AXIALTELESCOPING MOVEMENT OF THE LINER WITH RESPECT TO THE SHELL; PLACING AFOAMABLE PLASTIC